Flow control valves, such as ball valves or gate valves, can include a valve body or housing having an interior cavity and a fluid flow channel extending through the housing. For ball valves, a ball member may be located within the cavity and is provided with an axial throughbore, which is selectively aligned with, or disposed transverse to, the fluid channels in the housing, by rotating the ball member about an axis of rotation to control the flow of fluid through the fluid channels. For more robust services, such as undersea, or deep well valves, gate valves may provide more reliable sealing under harsh service conditions. For example, the well conditions may include high pressure, wide temperature ranges, the presence of corrosive fluids, sand particles, debris and the like. Additionally, some wells may experience a broad range of pressures. In low-pressure conditions, the gate valve may lose sealing integrity. Or, if the gate valve, ball valve, or other valve has been designed to seal tightly under low-pressure conditions, the valve may lose sealing integrity under high pressure conditions. Furthermore, a valve designed for low-pressure sealing may succumb to a faster rate of deterioration when subjected to high-pressure conditions. A number of valves have used various forms of seals, which have been formed of elastomeric or other non-metallic materials, and fitted at the locations required for sealing against fluid leakage.
In valve arrangements of the aforementioned type, seat life and fluid leakage has been a reoccurring problem.
Therefore, there is a need for a fluid flow control valve that obviates problems by providing a novel sealing member having an elastic range to exert a force capable of sealing under low-pressure and under high-pressure conditions.